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February 15, 2013

Another research paper on health impact of spay/neuter

Earlier this week, a new study from the folks at California-Davis was released discussing the potential health impact of spay/neuter -- and early spay/neuter. Cal-Davis has a long reputation as being a leader in veterinary medicine so the results of the study I think deserve to be taken seriously -- although with the caveat that I do believe there is a lot more research to be done in this arena.

The study looked exlusively at Golden Retrievers and separated the dogs into three groups:

1) Unaltered Golden Retrievers

2) Late-neutered Golden Retrievers (neutered after the age of 12 months)

Based on their study, the neutered dogs had significantly greater risk of several conditions than their unaltered counterparts.

- Neutered males were at significantly greater risk of developing Hip Dysplasia (HD) Early neutered males were at more than double the risk as late neutered males. Early spayed females were at greater risk, but there was no difference in femails between late spayed females and intact females.

- While there were no occurrances of Cranial Cruciate Ligament Tears (CCL) in unaltered animals, or late-spayed females, there was significant occurrance in early altered males and females. The suty points to the role of gonadal hormones in controlling the closure of bone growth plates and that an atypical growth plate closure (resulting from the absence of gonadal hormones, may increase the chance of a clinically apparent joint disorder such as CCL or HD.

- Early-neutered males and females were more likely to develop Lymphosarcoma (the 3rd most popular form of cancer in dogs) than those that were neutered late or left unaltered.

- While cases of Hermangiosarcoma were rare in unalterd dogs and early-neutered dogs, there was a significant occurrance of the cancer in late-spayed females. Previous studies have also linked the spay of female dogs to Hermangiosacrcoma.

- Mast cell tumors were not present in unaltered females, but were significantly more common in late spayed females and present in early spayed females.

The study concludes that while the role of gonadal hormones in joint growth seems to have a causal role in Cranial Cruciate Ligament Tears and Hip Dysplasia, it is more complicated in certain cancers. The study is also quick to point out that impact may be very different in other breeds of dogs that have different growth patterns or health issues.

This study joins a growing list of studies about the impact of spay/neuter on the health of dogs, with previous studies also showing strong evidence for the neutering of males to increased occurrance of prostate cancer, and another study linking the early neutering of Rottweilers to increase the likelihood of osteosarcoma (bone cancer). Again, this one was linked to the importance of hormones in bone growth in large-breed dogs.

The impact of the research being done in this area may have a significant impact on the animal welfare community. Spay/neuter has become a very common practice in the US, and a primary form of animal population control for companion animals. However, if we really are into animal welfare, then the overall health of animals needs to be a consideration. Additionally, if we are to remain credible as organizations working to help people's animals, we have to be aware, and honest, about health impacts of spay/neuter. We also need to be exploring other alternatives to spay/neuter such as vasectomies and tubal ligations that may have the same positive impact on population control, without removing the important growth hormones.

This also further highlights that pushes for government mandates of spay/neuter are ill-advised as they may over-ride the information coming from the veterinary community about what is best for canine health.

The amount of research being done in this area is growing. And while there appear to be solutions that all parties can benefit from, we need to be aware of the research so that we are knowledgable, aware of what I think will be the growing change in how we view spay/neuter in this country, and prepared to change our current practices based on the most current information available. Remaining ignorant on this topic, or hiding our heads in the sand will not change it or make it go away.

Comments

Thanks for sharing this. I have often wondered why they don't do vasectomies for male dogs, especially because it could encourage some owners who don't want them to be fully castrated (guys who don't want their dogs to lose their "balls").

Very tough subject. On the one hand one does not want to impact the health of the animal. On the other hand millions die in shelters each year and they did not come from the stork. I would like to say that responsible owner ship is the key but realistically just don't believe that will ever happen in our life time. Heck can't even get responsible owner ship for children in some cases. And then of course you have some folks that intentionally breed knowing that animals die in the shelters every day! If I could wave a majic wand I guess for me I would rather see some medical problems created by spay and neuter rather than millions EU'd in the shelters each year. Any other ideas?

Randy, it is a tough subject and I do think there is a John Stewart Mill "Greater Good" thing to consider.

However, I think we need to be careful to not tie ourselves to it's either this or that -- and explore other options -- including delaying the spay/neuter of puppies in shelters until they can fully mature, or better yet, explore other forms of sterilization that are less harmful than spay/neuter (like vasectomies/tubal ligations). There may be unexplored options where we can have the best of both worlds.

Good thoughts Brent. I know at least from a shelter view point the delay of spaying and neutering presents two concerns. One-If you delay and still hold in the shelter then you have space issues. Plus the younger ones are more eaisly adopted. Two-if you release the yonger non fixed animals to new owners even with a prepaid spay and neuter the return rate for the spay and neuter procedure is not good even under threat of citation. Read as you have breeding potential dogs out there. Now I like the vasectomy/tubal idea a bunch. Guess the question would be how much more complicated is that for the vet which might trnslate into more $. Way beyond my area of expertise to answer!

Randy, our experience with sending animals out unaltered and having them return for surgery has been pretty good. Most people want altered pets, and are happy to do so. We occassionally have issues with people coming back, but rarely.

And yes, the idea of tubal ligation/vasectomy is not mine, nor do I know of the complications/costs/challenges of that surgery to spay/neuter -- nor are we certain of the health impacts of that, but I have to believe it would be less intrusive than full spay/neuter and removing the hormones from the body development.

My experience in Texas was we had about a 10% non return rate. Various reasons given. Moved, animal deceased, animal given away etc. Perhaps some valid perhaps some not. Took a fair amount of staff time to follow up. Hence the move to younger spay and neuter. One could argue if that was right but it was done to address a preceived problem. ie. non altered animals. I guess numbers would vary by facility. 10% does not sound like much but at even 1,000 animals per year adds up. Much less a facility that may take in tens of thousands. It is good to hear you are having good success with your rates. I know there are some groups that advocate marketing and adoptions primarily. And some that advocate spay an neuter primarily. Given the size of the issue it would seem like a joint approach would be appropriate. The good news is the more focus on the issue the more likely hood of a resolution! Appreciate the time and effort you have put in on this blog. Quite frankly its the only one I know of that attempts to present both sides of each issue in a non emotional lets see if we can address the problem forum! Thanks heaven too at lest to date it has not been over run by folks with "other agenda's" and taken off topic. Thanks for the good work!

Thanks Randy - and thanks for adding to the discussion. I always hope this can remain a place for intelligent debate because if we quit debating some of the issues, or ignoring them, we will lose a lot of good ideas for success.

So far, it doesn't appear to me that the likelihood of bad effects are high enough for any individual dog to make early spay/neuter unacceptable as a shelter practice. 10% non-return rate actually seems reasonably low to me, especially given that some of those non-returns are likely to be people who preferred to use their own vet. But on the other hand, none of the dogs in shelters should be reproducing, so I don't have a problem with early spay/neuter in that context.

Once an intact animal is in a responsible home, though, the owners of that animal have a right to be fully informed on BOTH the risks and the benefits of early or late spay/neuter. Most people want altered pets; however, many might choose to alter later rather than earlier if they knew there are health consequences to the choice.

I have been so upset since i read this a few days ago. I've been searching the internet for more research. If anyone has any additional research on the adverse health effects of spay/neuter I want to read it. Please send it to ZiaSavesDogs at gmail dot com. I am a board member for a spay/neuter clinic and would like all the info i can get my hands on.

I have a pit bull who is currently 3 days out of her 2nd ccl (canine cruciate ligament surgery) She was spayed at 8 weeks old. Which makes sense according to the study and also really upsets me.

This does beg the question, do we wait till they are all 1 year old? Do we sacrifice dog health until the dog population is under control in the US (due to euthanasia #'s)? What does this mean for us, animal advocates and spay/neuter clinics?

Zia -- I agree that this is a challenging question, but I really appreciate you wanting to ask the question "what does this mean to us?" And no, I don't believe we know all the answers yet. By all accounts, waiting until dogs are older to spay/neuter seems definitely in order. I also think exploring other means of sterilization (that don't eliminate growth hormones) is in order. I don't think we can run from this one -- and the sooner we tackle it the better off we'll be. I fear the potential public backlash from the public on the rescue community if we DON'T address it. Because if we're not concerned about the health of animals (which admittedly, does include them dying in shelters), then we shouldn't be in this.

BTW Zia - if you go into the link to the full article, it cites most of the existing research on this topic and you can probably find some of them online. Ted Keresote also addresses some of this in his newest book -- and once I get to that part I'll be posting more about it for sure.

Lis -- I have to confess that I'm really concerned about this. On one hand there is an understandably huge concern about the number of pets out there, and shelter deaths, and the importance of spay/neuter in minimizing this. On the flip side, I do think public awareness of the risks is growing (mine certainly is), and what happens when 10-20% of the population of new pet owners opt against adoption because they don't want their pet spay/neutered, or don't want it done at such a young age? I know the 10% chance of Hip Dysplasia, or 8% chance of cruciate ligament repair or the 10% likelihood of lymphoma would make me think twice about adopting a young puppy that was already altered.

Zia -- here is another article (if you were searching online you probably found it) by Laura Sandborn on the topic from several years ago. All of the data is sources, so another resource for the research on the topic: